/* Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335  USA */

#include "sql_cache.h"                         /* Query_cache_block */

class Querycache_stream
{
  uchar *cur_data;
  uchar *data_end;
  Query_cache_block *block;
  uint headers_len;
public:
#ifdef DBUG_ASSERT_EXISTS
  Query_cache_block *first_block;
  uint stored_size;
#endif
  Querycache_stream(Query_cache_block *ini_block, uint ini_headers_len) :
    block(ini_block), headers_len(ini_headers_len)    
  {
    cur_data= ((uchar*)block)+headers_len;
    data_end= cur_data + (block->used-headers_len);
#ifdef DBUG_ASSERT_EXISTS
    first_block= ini_block;
    stored_size= 0;
#endif
  }
  void use_next_block(bool writing)
  {
    /*
      This shouldn't be called if there is only one block, or to loop
      around to the first block again. That means we're trying to write
      more data than we allocated space for.
    */
    DBUG_ASSERT(block->next != block);
    DBUG_ASSERT(block->next != first_block);

    block= block->next;
    /*
      While writing, update the type of each block as we write to it.
      While reading, make sure that the block is of the expected type.
    */
    if (writing)
      block->type= Query_cache_block::RES_CONT;
    else
      DBUG_ASSERT(block->type == Query_cache_block::RES_CONT);

    cur_data= ((uchar*)block)+headers_len;
    data_end= cur_data + (block->used-headers_len);
  }

  void store_uchar(uchar c);
  void store_short(ushort s);
  void store_int(uint i);
  void store_ll(ulonglong ll);
  void store_str_only(const char *str, uint str_len);
  void store_str(const char *str, uint str_len);
  void store_safe_str(const char *str, uint str_len);

  uchar load_uchar();
  ushort load_short();
  uint load_int();
  ulonglong load_ll();
  void load_str_only(char *buffer, uint str_len);
  char *load_str(MEM_ROOT *alloc, uint *str_len);
  int load_safe_str(MEM_ROOT *alloc, char **str, uint *str_len);
  int load_column(MEM_ROOT *alloc, char **column);
};

uint emb_count_querycache_size(THD *thd);
int emb_load_querycache_result(THD *thd, Querycache_stream *src);
void emb_store_querycache_result(Querycache_stream *dst, THD* thd);